Mechanism for a chair



FIG. 1 is a top, front and left side perspective view of mechanism for a chair showing our design;

FIG. 2 is a right side elevational view thereof;

FIG. 3 is a left side elevational view thereof;

FIG. 4 is a top plan view thereof; and,

FIG. 5 is a front elevational view thereof. 

The ornamental design for mechanism for a chair, as shown. 